Bad shore power
 

There is another thtread about someone with a bad shore power
connection and what to do with it. I agree, the guy has no right to
endanger others. I consider myself to be a fairly knowledgeable person
but had never had my boat in a marina and never had shore power so I
was not familiar with the dangers. When cruising, we stayed in a
marina for the first time. I decided to swim to check my prop for
fouling as I always did.
The water felt really strange, sorta tingly all over. My shaft zinc
that had just been installed a month ago was nearly gone. I was in
mask and snorkel looking at it trying to figure it out when it suddenly
occurred to me, ELECTRICITY! I swam away from the boats without
touching anything and got out of the water at the shore. Sure enough,
the guy next to me had a bizarro shore power cord with two prongs, just
regular zip cord.

Bad shore power
 

wrote:
There is another thtread about someone with a bad shore power
connection and what to do with it. I agree, the guy has no right to
endanger others. I consider myself to be a fairly knowledgeable person
but had never had my boat in a marina and never had shore power so I
was not familiar with the dangers. When cruising, we stayed in a
marina for the first time. I decided to swim to check my prop for
fouling as I always did.
The water felt really strange, sorta tingly all over. My shaft zinc
that had just been installed a month ago was nearly gone. I was in
mask and snorkel looking at it trying to figure it out when it suddenly
occurred to me, ELECTRICITY! I swam away from the boats without
touching anything and got out of the water at the shore. Sure enough,
the guy next to me had a bizarro shore power cord with two prongs, just
regular zip cord.


Just curious: sal****er or fresh?

Chuck

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Bad shore power
 

I don't want to rain on your parade here, but bad shore power is very common
and the guy next door is not causing it. The problem is that there is at
least one consumer on your distribution transformer that has a current leak
to safety ground. In an ideal world that leak should flow to earth through
the neutral to safety earth connection at the distribution transformer, but
as you are in a marina and your hull earth is a lot better than the corroded
earth rod at the transformer, the energy leak is flowing through your hull.
That is the reason for using an isolation transformer. In any case never
connect the shore point safety earth to your hull. Do exactly like your
neighbor did, connect only phase and neutral. On your boat make certain all
safety earth connections connect to your hull only. It is just as safe for
YOU, but the dock has a serious SAFETY issue. Any person touching a dock
earthed point and the water could be shocked. This is NOT code, but the
shock is significantly less on your wallet.
Steve

wrote in message
oups.com...
There is another thtread about someone with a bad shore power
connection and what to do with it. I agree, the guy has no right to
endanger others. I consider myself to be a fairly knowledgeable person
but had never had my boat in a marina and never had shore power so I
was not familiar with the dangers. When cruising, we stayed in a
marina for the first time. I decided to swim to check my prop for
fouling as I always did.
The water felt really strange, sorta tingly all over. My shaft zinc
that had just been installed a month ago was nearly gone. I was in
mask and snorkel looking at it trying to figure it out when it suddenly
occurred to me, ELECTRICITY! I swam away from the boats without
touching anything and got out of the water at the shore. Sure enough,
the guy next to me had a bizarro shore power cord with two prongs, just
regular zip cord.

Bad shore power
 

wrote:
There is another thtread about someone with a bad shore power
connection and what to do with it. I agree, the guy has no right to
endanger others. I consider myself to be a fairly knowledgeable person
but had never had my boat in a marina and never had shore power so I
was not familiar with the dangers. When cruising, we stayed in a
marina for the first time. I decided to swim to check my prop for
fouling as I always did.
The water felt really strange, sorta tingly all over. My shaft zinc
that had just been installed a month ago was nearly gone. I was in
mask and snorkel looking at it trying to figure it out when it suddenly
occurred to me, ELECTRICITY! I swam away from the boats without
touching anything and got out of the water at the shore. Sure enough,
the guy next to me had a bizarro shore power cord with two prongs, just
regular zip cord.

Hi:

Well what ever yo do not take the advice of Granny Rosalie.
She wold most likly tell you that it was you own damn falt for being in
the water.
Or as she said in another post.....................

"...We were taught to assess probability (how likely something was to
happen) and hazard (how severe the problem would be if it happened).
In this case... would not trip would be very great, but the probability
would be low.
You can think of almost any
scenario where there is a possibility of something happening. That
doesn't mean that it is probable....."
Rosalie B.

"So why would you be going in the water anyway for? Don't ya know that
water is dangerous?"

Bob

Bad shore power
 

Steve Lusardi wrote:
I don't want to rain on your parade here, but bad shore power is very common
and the guy next door is not causing it. The problem is that there is at
least one consumer on your distribution transformer that has a current leak
to safety ground. In an ideal world that leak should flow to earth through
the neutral to safety earth connection at the distribution transformer, but
as you are in a marina and your hull earth is a lot better than the corroded
earth rod at the transformer, the energy leak is flowing through your hull.
That is the reason for using an isolation transformer. In any case never
connect the shore point safety earth to your hull. Do exactly like your
neighbor did, connect only phase and neutral. On your boat make certain all
safety earth connections connect to your hull only. It is just as safe for
YOU, but the dock has a serious SAFETY issue. Any person touching a dock
earthed point and the water could be shocked. This is NOT code, but the
shock is significantly less on your wallet.
Steve

wrote in message
oups.com...
There is another thtread about someone with a bad shore power
connection and what to do with it. I agree, the guy has no right to
endanger others. I consider myself to be a fairly knowledgeable person
but had never had my boat in a marina and never had shore power so I
was not familiar with the dangers. When cruising, we stayed in a
marina for the first time. I decided to swim to check my prop for
fouling as I always did.
The water felt really strange, sorta tingly all over. My shaft zinc
that had just been installed a month ago was nearly gone. I was in
mask and snorkel looking at it trying to figure it out when it suddenly
occurred to me, ELECTRICITY! I swam away from the boats without
touching anything and got out of the water at the shore. Sure enough,
the guy next to me had a bizarro shore power cord with two prongs, just
regular zip cord.




Hello Steve,

I would caution strongly against using the
water-earth path in lieu of the green equipment
grounding conductor. Ever.

The purpose of that conductor is to provide a low
impedance path for the purpose of clearing a
ground fault.

In proper wiring, the impedance is no more than a
few ohms and the fault is cleared at a breaker.
Fault current does NOT flow through the earth.

By contrast, the water-earth path may have a
resistance of 25 ohms or more for salt water, and
tens of thousands of ohms or more for fresh water.
This path will NOT clear a ground fault. It will
not trip a 20 A breaker. Witness the 120 volt
power cords dropped off a dock without tripping a
breaker!

If one has a problem with wiring impedances in the
marina, deal with it by getting the wiring
inspected. Ask the marina operator when it was
last checked. Yell. Scream. Buy your own tester
and tell the marina what you measured. Tell the
other boaters. Take names and publish on the
Internet. But don't throw out the safety net
because even with corroded connections, the wiring
may still allow a ground fault to be cleared.

If there is a problem with a nearby source (boat
or otherwise) then an isolation transformer would
be a good idea.

But even with an isolation transformer, always use
approved wiring practices. There is probably no
more thoroughly reviewed standard than the NEC.
The ABYC standards for AC wiring are similarly solid.

And install GFCIs for the smaller ground fault
currents that won't trip a regular breaker but can
electrocute.

Good luck.

Chuck



















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Bad shore power
 

Hmm.

Seems to me GFCIs pop if there is a difference between hot and neutral
wire currents. Don't rely on ground. If all the current that comes in
doesn't return the way it's supposed to, it turns off. It's a
differential amp that does it and toroidal coil assemblies. The test
button might need earth, so it can trip the circuit by cheating. Proper
ones don't.

The Earth should not be electrified, nor the Sea neither. It's bad
enough that we might inadverdently offer the possibility for current to
flow into the earth by touching a live wire, but if the power company
hadn't hooked the earth to the power line, it's wouldn't have any where
to leak to whilst electrocuting you.

Aboard, if metal parts are earthed, earth the plug, otherwise, it
don't matter. Sea water in the bilge sort of grounds wet stuff, but
it's moot.

There are several possible faults that are best protected by
contradictory means. It's a question of probability and risk
assessment.

It's your boat. Read your insurance documents for electrical
requirements, survey report required? Marinas don't seem to care. Old
boats may be grandfathered. Fire is the real danger.

Terry K

Bad shore power
 

So were you using shore power when that happened?


wrote:
There is another thtread about someone with a bad shore power
connection and what to do with it. I agree, the guy has no right to
endanger others. I consider myself to be a fairly knowledgeable person
but had never had my boat in a marina and never had shore power so I
was not familiar with the dangers. When cruising, we stayed in a
marina for the first time. I decided to swim to check my prop for
fouling as I always did.
The water felt really strange, sorta tingly all over. My shaft zinc
that had just been installed a month ago was nearly gone. I was in
mask and snorkel looking at it trying to figure it out when it suddenly
occurred to me, ELECTRICITY! I swam away from the boats without
touching anything and got out of the water at the shore. Sure enough,
the guy next to me had a bizarro shore power cord with two prongs, just
regular zip cord.

Bad shore power
 

Terry K wrote:
Hmm.

Seems to me GFCIs pop if there is a difference between hot and neutral
wire currents. Don't rely on ground. If all the current that comes in
doesn't return the way it's supposed to, it turns off. It's a
differential amp that does it and toroidal coil assemblies. The test
button might need earth, so it can trip the circuit by cheating. Proper
ones don't.


GFCIs work at 125 volts only so they are usually
not the sole solution.

The Earth should not be electrified, nor the Sea neither. It's bad
enough that we might inadverdently offer the possibility for current to
flow into the earth by touching a live wire, but if the power company
hadn't hooked the earth to the power line, it's wouldn't have any where
to leak to whilst electrocuting you.

Aboard, if metal parts are earthed, earth the plug,

Disagree. Any appliance with a 3-prong plug will
lose the protection built into it if the ground
wire is not connected, unless it is protected by a
GFCI. But if that appliance develops a ground
fault (hot wire shorted directly to metal case) it
will not trip the GFCI unless some one or thing
provides a path to earth. Meanwhile, if it is,
say, an electric drill (3-prong plug), you are
walking around your boat holding the hot 125 vac
wire in your hand!

Surely we don't want to be suggesting that people
"game" the wiring system and thereby disable
built-in protections.

Chuck



otherwise, it
don't matter. Sea water in the bilge sort of grounds wet stuff, but
it's moot.

There are several possible faults that are best protected by
contradictory means. It's a question of probability and risk
assessment.

It's your boat. Read your insurance documents for electrical
requirements, survey report required? Marinas don't seem to care. Old
boats may be grandfathered. Fire is the real danger.

Terry K


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Bad shore power
 

chuck wrote:
Terry K wrote:
Hmm.

Seems to me GFCIs pop if there is a difference between hot and neutral
wire currents. Don't rely on ground. If all the current that comes in
doesn't return the way it's supposed to, it turns off. It's a
differential amp that does it and toroidal coil assemblies. The test
button might need earth, so it can trip the circuit by cheating. Proper
ones don't.


GFCIs work at 125 volts only so they are usually
not the sole solution.

The Earth should not be electrified, nor the Sea neither. It's bad
enough that we might inadverdently offer the possibility for current to
flow into the earth by touching a live wire, but if the power company
hadn't hooked the earth to the power line, it's wouldn't have any where
to leak to whilst electrocuting you.

Aboard, if metal parts are earthed, earth the plug,

Disagree. Any appliance with a 3-prong plug will
lose the protection built into it if the ground
wire is not connected, unless it is protected by a
GFCI. But if that appliance develops a ground
fault (hot wire shorted directly to metal case) it
will not trip the GFCI unless some one or thing
provides a path to earth. Meanwhile, if it is,
say, an electric drill (3-prong plug), you are
walking around your boat holding the hot 125 vac
wire in your hand!

Surely we don't want to be suggesting that people
"game" the wiring system and thereby disable
built-in protections.

Chuck



otherwise, it
don't matter. Sea water in the bilge sort of grounds wet stuff, but
it's moot.

There are several possible faults that are best protected by
contradictory means. It's a question of probability and risk
assessment.

It's your boat. Read your insurance documents for electrical
requirements, survey report required? Marinas don't seem to care. Old
boats may be grandfathered. Fire is the real danger.

Terry K


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I dont even have any connections for shore power so am not sure how my
boat was making any sort of connection. I'd never spent any time in a
marina so didnt know swimming near other boats was an issue till then.

Bad shore power
 

wrote:
chuck wrote:
Terry K wrote:
Hmm.

Seems to me GFCIs pop if there is a difference between hot and neutral
wire currents. Don't rely on ground. If all the current that comes in
doesn't return the way it's supposed to, it turns off. It's a
differential amp that does it and toroidal coil assemblies. The test
button might need earth, so it can trip the circuit by cheating. Proper
ones don't.

GFCIs work at 125 volts only so they are usually
not the sole solution.

The Earth should not be electrified, nor the Sea neither. It's bad
enough that we might inadverdently offer the possibility for current to
flow into the earth by touching a live wire, but if the power company
hadn't hooked the earth to the power line, it's wouldn't have any where
to leak to whilst electrocuting you.

Aboard, if metal parts are earthed, earth the plug,
Disagree. Any appliance with a 3-prong plug will
lose the protection built into it if the ground
wire is not connected, unless it is protected by a
GFCI. But if that appliance develops a ground
fault (hot wire shorted directly to metal case) it
will not trip the GFCI unless some one or thing
provides a path to earth. Meanwhile, if it is,
say, an electric drill (3-prong plug), you are
walking around your boat holding the hot 125 vac
wire in your hand!

Surely we don't want to be suggesting that people
"game" the wiring system and thereby disable
built-in protections.

Chuck



otherwise, it
don't matter. Sea water in the bilge sort of grounds wet stuff, but
it's moot.

There are several possible faults that are best protected by
contradictory means. It's a question of probability and risk
assessment.

It's your boat. Read your insurance documents for electrical
requirements, survey report required? Marinas don't seem to care. Old
boats may be grandfathered. Fire is the real danger.

Terry K

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I dont even have any connections for shore power so am not sure how my
boat was making any sort of connection. I'd never spent any time in a
marina so didnt know swimming near other boats was an issue till then.


It's difficult to speculate intelligently, but AC
is thought to be much less of a problem in causing
galvanic corrosion than DC, so I would concentrate
on finding a DC current path to explain the rapid
zinc depletion. Being in the field of an impressed
current system on a larger vessel could do it, for
example.

AC fields in salt water usually don't cause safety
problems for swimmers because the swimmer's body
is effectively shorted out by the much greater
conductivity of the surrounding seawater. Imagine
(but don't do it!) standing on an insulating
surface and touching a bare, hot 120 VAC wire with
both hands 1 foot apart. Since the resistance of
the wire is so much less than the body's
resistance, you feel nothing and live to tell
about it. A swimmer in a strong electrical field
in sal****er experiences the same effect. In fresh
water, however, you'd be toast.

Chuck

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